Respiratory Physiology 2 Flashcards
What is the definition of dalton’s law?
How gases move down their concentration gradient by diffusion
What is the definition of Henry’s law?
How the solubility of a gas relates to its diffusion
Internal respiration
Oxygenated blood turns into deoxygenated blood as O2 and CO2 move down their partial pressure gradients- either back into blood or into tissue
Each haemoglobin molecule transports how many oxygen molecules?
4 O2 molecules
What does oxygen level measure?
Amount of oxygen dissolved in the plasma
What is haemoglobin’s structure?
4 polypeptide chains: 2 alpha and 2 beta
4 haem groups ( 1 bound to each polypeptide chain)
What is the structure of the haem group?
Porphyryn ring with an iron ion in the centre
Each iron ion in haem group binds to howmany molecules of o2?
1- can bind to molecule of oxygen in a reversible manner
Why is the Saturation of Hb-O2 and partial pressure graph of oxygen sigmoidal?
Difficult for first molecule to bind to haem group
Conformational change, make easier for rest to bind
Full saturation hard to achieve because only one haem group left for fourth molecule of O2, harder for O2 to find it
How is most oxygen transported?
Being bound to Hb
What is the Bohr Effect?
In tissues that need more O2, the local environment moves hB-O2 curve to the right aiding unloading of O 2
What factors cause the sigmoidal curve to move to the left?
Low CO2 concentration environments
High pH concentrations
Fetal blood- higher affinity for o2 than mother
What does partial pressure of O2 measure?
Dissolved oxygen not oxygen carried by Hb
So pp of O2 in blood is the same even if amount of haemoglobin decreased to half=anaemia
How is CO2 carried in the blood? (3 ways)
Dissolved in plasma
Bicarbonate (H2CO3 which dissociates to H+ and HCO3-)= main one
Carbamino compounds
Method of how CO2 gets into blood
CO2 enters blood
High levels of carbonic anhydrase catalysing the reaction between CO2 and water to carbonic acid
Carbonic acid dissociates to hydrogen carbonate ions and hydrogen ions.
Hydrogen carbonate ions move out of erythrocyte into plasma via diffusion
Negatively charged chloride ions move in to maintain electrical balance of cells=chloride shift
How Co2 leaves blood at lungs
Low conc of CO2
Carbonic anhydrase catalyses reverse reaction breaking down carbonic anhydrase to CO2 and H20
Carbonic anhydrase diffuse back into erythrocyte react with H+ to form carbonic acid then broken down to produce CO2 and H20. Co2 diffuse out of blood into lungs
What acts as a buffer in blood?
Haemoglobin will bind with the H+ to form haemoglobinic acid from the dissocation of carbonic acid and from dissociation of carbaminohaemoglobin that forms H+ and carbamino group
How does the amount of CO2 in the blood affect the amount of O2 in blood?
The more CO2 there is the less O2 that can be carried.
HbO2 + H+ lead to HbH+ + O2
What is the Haldane effect?
CO2 loading/unloading enhanced by O2 unloading/loading respectively
How do baroreceptors play a part in respiration? Where are they located?
Stimulate respiration in response to hypotension (aortic and carotid bodies)
Signals are send from the respiratory centre in the medulla to the muscles involved in breathing through which nerves?
Phrenic and intercostal nerves
How do chemoreceptors play a part in respiration? Where are they?
Respond to decreases in oxygen and metabolic acidosis, also responds to changes in pH of cerebrospinal fluid
How do mechanoreceptors play a part in respiration?Where are they?
Stimulate respiration in response to exercise- in muscles/joints
